コーディング用ツールのインターフェース（Read、Edit、Bash）

コードエージェントに必要なツールとは

read_file

def read_file(path: str, start_line: int = 0, end_line: int | None = None) -> str:
    with open(path) as f:
        lines = f.readlines()
    return ''.join(lines[start_line:end_line])

# --- demo ---
with open('demo_source.py', 'w', encoding='utf-8') as f:
    f.write('line0\nline1\nline2\nline3\nline4\n')

snippet = read_file('demo_source.py', start_line=1, end_line=3)
print('Lines 1-2 of demo_source.py:')
print(snippet)

行範囲を指定した読み取りでトークンを節約する

edit_file（文字列置換）

def edit_file(path: str, old_string: str, new_string: str):
    contents = read_file(path)
    occurrences = contents.count(old_string)
    if occurrences == 0:
        raise ValueError('old_string not found')
    if occurrences > 1:
        raise ValueError('old_string is not unique')
    contents = contents.replace(old_string, new_string)
    with open(path, 'w') as f:
        f.write(contents)

差分より文字列置換を使う理由

write_file

def write_file(path: str, content: str):
    os.makedirs(os.path.dirname(path), exist_ok=True)
    with open(path, 'w') as f:
        f.write(content)

bash

def bash(command: str, timeout: int = 60) -> dict:
    import subprocess
    try:
        result = subprocess.run(command, shell=True, capture_output=True, text=True, timeout=timeout)
        return {'stdout': result.stdout[-5000:], 'stderr': result.stderr[-5000:], 'exit_code': result.returncode}
    except subprocess.TimeoutExpired:
        return {'error': 'timeout', 'exit_code': -1}

# --- demo ---
result = bash("echo hello from the sandboxed shell")
print(f"exit_code={result['exit_code']}")
print(f"stdout={result['stdout'].strip()!r}")

bashツールをサンドボックス化する

長い出力を切り詰める

stderr = 'error line\n' * 1000

if len(stderr) > 5000:
    stderr = '...[truncated]...' + stderr[-5000:]

print(f'Truncated stderr length: {len(stderr)}')

search / grep

def grep(pattern: str, path: str = '.', file_glob: str = '**/*') -> list[str]:
    matches = []
    for f in glob(file_glob, recursive=True):
        for i, line in enumerate(open(f)):
            if re.search(pattern, line):
                matches.append(f'{f}:{i+1}: {line.rstrip()}')
    return matches[:50]

list_files

def list_files(path: str = '.') -> list[str]:
    return [p for p in glob(f'{path}/**', recursive=True) if os.path.isfile(p)][:200]

オプション：ASTツール

def find_function(name: str, path: str):
    tree = ast.parse(open(path).read())
    for node in ast.walk(tree):
        if isinstance(node, ast.FunctionDef) and node.name == name:
            return ast.unparse(node)

ここではツールの説明が最も重要

description='Edit a file by replacing a unique string. The old_string MUST appear exactly once in the file. Reads the file first to validate. Use this for any code change in an existing file.'

これがツールセット全体です

編集パターン

まとめ